This project is concerned with the synthesis and biologic evaluation of selenium containing analogs of aromatic amino acids as imaging agents for the detection and differential diagnosis of carcinoma of the pancreas and with selenium containing analogs of metryapone as imaging agents for analysis of adrenal cortex pathology. The research goals for the current year include making four selenium containing tryptophan analogs and one histidine analog and a series of 1,3,4-selenadiazole and 1,3-selenazole metyrapone analogs. These compounds will be administered to rats to determine their pharmacokinetics biologic distribution, toxicity and ultimate fate. Selenium levels in the tissues will be determined by neutron activation analysis. The amino acids that show in vivo stability and promising pancreas to liver ratios, adrenal to liver and adrenal to kidney ratios, will be labeled with 75Se and then reevaluated using the gamma well counter to determine tissue distribution. 75Se-2-selenienylalanine is a compound currently being examined at this level.